Cooling unit for refrigeration purposes



March 23, 1937. 2,074,700

COOLING IlJNIT REFRIGERATION PURPOSES I A. s. LIMEERT Filed Nov. 21,1932 INVEIT R:

mAT-roRNEY.

Marh 23, 1937. A. s. LIMPE RT COOLING UNIT FOR REFRIGERATION PURPOSESFiled Nov. 21, 1932 7 Sheets-Sheet 3 INVENT'RI' flZATTORNEY.

March 23, 1937. A. s. LIMPERT 2,074,700

COOLING UNIT FOR REFRIGERATION PURPOSES Filed Nov. 21, 1952 7Sheets-Sheet 4 Q 7 lNV T9R:.

' .fl ATTORNEY.

MarcF 23, 1937. A.IS..LIMPERT COCLING UNIT FOR REFRIGERATION PURPOSESFiled Nov. 21, 1952 7 Sheets-Sheet 5 I V INVE T -3 5 Q MXW I BY fld'ATTORNEY.

March 23, 1937. A. s. LIMPERT CObLING UNIT FOR REFRIGERATION PURPOSESFiled Nov. 21, 1932 7 Sheets-Sheet 6 March 23,1937. A, s, LIMPERT2,074,700

COOLING UNIT FOR REFRIGERATION PURPOSES Filed Nov. 21, 1932 '7Sheets-Sheet 7 ZATTORNEY.

Patented Mar. 23,1937

UNITED STATES PATENT OFFICE COOLING UNIT FOR REFRIGERATION PURPOSESApplication November 21, 1932, Serial No. 643,695

4 Claims.

This invention relates to apparatus which is peculiarly suited for useas a cooling unit of an automatic refrigerator wherein an efficient,sturdy, compact, cheap and attractively designed unit is a matter ofprime consideration. The

further objects of the invention are the provision of a construction anda method of making same whereby such unit can be formed from ferrous ornon-ferrous metals as a result of either a casting, a die-stamping orpressure diecasting operation and which unit readily lends itself tobeing finished in enamel. Other objects of the invention are hereinafterset forth.

Heretofo-re it has been proposed to cast a tube of high conductivity,such as copper, for example, in a wall of metal of lower melting point,such for example as type metal, or other zinc alloys or even aluminum,but while tanks having such coils cast in the walls thereof are quiteefficient as cooling units, nevertheless, there are some objections,such as the difficulties of cast-- ing, the susceptibility of tubingsuch as copper, to form scale on the inside thereof during the castingoperation, which scale tends to often lodge in valve-seats and bearingsand other portions of a mechanical refrigerating machine and also thetendency to form air pockets between the coil and the metal wall inwhich the same is embedded due to the difference in the coefficients ofexpansion of the two metals. Also such cooling units cannot be enameledsatisfactorily, since in the enamelling operations the temperatures areso high as to in many cases burn the coil besides forming scale asaforesaid, therein. Neither isit considered practicable at the presenttime to form such tanks of ferrous metal, such as steel or iron, as itis extremely difficult, if not impossible, to satisfactorily cast a coiltherein unless the coil is of some expensive high melting point steel orother alloy and furthermore, the forming of such a coil is itself anextremely difficult and expensive operation.

My investigations have led to the discovery that the aforesaidobjections can be effectively overcome and a cooling unit which isremarkably efficient can be constructed by following the method setforth in detail in the following description and drawings forming a partthereof.

Referring to the drawings wherein I have illustrated differentembodiments of the invention Figure l is aside elevation;

Fig. 2 a rear elevation; 1

Fig. 3 is a ver i al l g tud nal section of a sectional freezing unitshowing one form of the invention;

Fig. 4 is a transverse vertical section onthe line 4-4 of Fig. 3;

Figs. 5, 6 and '7 are horizontal sections on the lines 5-5, 6-% and 1-1respectively of Fig. 3;

Fig. 8 is a longitudinal vertical section of a modification wherein themain body comprises a casting and in which all the pressure plates areinternally disposed; Fig. 9 is a fragmentary detail horizontal sectiononthe line 9-9 of Fig. 8; and

Fig. 10 is a section on the line l0l0 of Fig. 8;

Fig. 11 is a front elevation of a still further modification having anultra-rapid freezing compartment; Fig. 12 is a plan view, partly brokenaway of the same unit and Fig. 13 is a perspective view, partly cutaway, of one of the small sections of the same unit.

Fig. 14 is a plan View of one of the intermediate units of Fig. 11; Fig.15 is a detail frag-- mentary vertical section on the line |5--|5 ofFig. 14. and Fig. 16 is a vertical section, partly interrupted of Fig.11.

Fig, 1'7 is a vertical transverse section of a still further type ofunit.

Now, referring to the construction shown in the drawings, the type ofunit illustrated in Figs. 1 to 3 and 6 to 8, comprises a built-up orsectional unit formed of two main castings or sections I and 2respectively, the larger or upper one being of suflicient size toreceive what is known as a pudding tray and the lower section on whichit is superimposed being of a size to receive the usual cube tray. Thebottom 3 of'section l and the top 4 of section 2 (Fig. 3) are virtuallyidentical except that their position is reversed and each of the same isprovided with front flanges 5 and 6 respectively. The top 1 of sectionI' and the bottom 8 of section 2 .are also identical but reversed inposition; and these sections have substantially continuous marginalflanges 9 and II), respectively, that extend along all edges thereof,Integral cored bosses H, H and l2, [2 are formed on the sides of thecasting I and 2 (see Fig. 1). The bosses II and I2 are provided withradiating fins or vanes l3, l3 and additional fins I4, M are formed onthe side walls of sections I and 2. The size and number of such fins isdetermined according to the extent that it is desired to increase thesuperficial area of the unit and thereby the consequent cooling effectof such unit upon the air of the refrigerator can be regulated, thuspermitting of a relatively small unit being equally serviceable eitherfor a refrigerator of relatively small capacity or for the cooling ofrefrigerators of considerably larger capacity while at the same timeadmitting of the rapid freezing of ice cubes in trays positioned withinthe cooling unit proper. 5 The cooling coil [5, through which therefrigerant is circulated for the purpose of maintaining the coolingunit at the desired temperature, preferably comprises metallic tubing,preferably of lead, because of its pliability, which tubing isoriginally circular in cross-section and which is first bent to apredetermined loop formation, such as illustrated in Figs. 5, 6 and '7.Such looped tubing or so-called coil is then applied to the surfaces aand b and 0 (see Fig. 3), and thereafter flattened to a substantiallyelliptical formation by means of a dummy or master pressure plate whichis forced under considerable pressure, either mechanical or hydraulic,against such coils, while they are in position on the supportingsurface, until the said coils assume the flattened or ellipticalcross-sectional configuration shown in Figs. 3 and 4, for example.

As shown, the coil I5 is connected at the top of the unit to the intakefitting l6 carried by a top pressure plate I! (Fig. 3) and, as shown inFig. 5, is looped to form a circuitous path so as to effectively cover,insofar as its heat-exchange effect is concerned, the top face 0 of theupper unit. From the space d between the top of section 2 and pressureplate 11, the coil passes downwardly through a groove or channel l8formed in the boss H! to the space e immediately above the top face I)of the lower section, where it is caused to assume the looped formationshown in Fig. 6. It emerges from said space through the same aperturethrough which it entered the same and passes downwardly through thechannel l8 in the boss H! to the space I immediately below the lowerface a of the bottom section 3 in which space such coil is looped in themanner illustrated in Fig. 7 and just before it emerges from such space,the straight leg g of said coil passes in proximity to a thermostaticwell 20, thence passing into the groove or channel in the boss 2| andthrough the registering groove 2! in the boss 22' directly up to thespace d above the top section where it connects with the outlet fitting23. A bottom pressure plate 24 is applied to the bottom of the sectionI, such pressure plate being generally similar in configuration to thetop pressure plate I1. As shown (Fig. 1) the top and bottom pressureplates I1 and 24 are provided with marginal cored bosses 25 and marginalspacing flanges 26, 26', which latter serve to maintain them inpredetermined spaced relation with respect to the face of the particularsection to which the same are applied, and consequently render itpossible to maintain intimate metal-to-metal contact between the sidesof the elliptical or flattened coil and adjacent surfaces of thesections and of the pressure plates respectively, while preventing unduecollapse of such coil, all as illustrated in Figs. 3 and 4. Ordinarycarriage bolts 2'! are inserted into cored registering openings in thebosses H, II, l2, I2 and 25, which are adapted to receive the same, theheads h of said bolts being enlarged cross-section with respect to thediameter of the cored openings in the aforesaid V bosses; Nuts 28 arethreaded on the upper ends of said bolts and said latter nuts serve toalso secure front and rear bracket members 29, 29 to said unit, whichserve for supporting the unit in any desired location within the coolingchamber of the refrigerator. Preferably skeleton gaskets 6f waterproofedfiber, or of copper and asbestos or of lead, such as illustrated by thereference letter 10, are interposed between the abutting surfaces of theadjacent sections or the abutting surfaces of a section and a pressureplate applied thereto. As illustrated in Fig. 4, the upper section ofthe unit is preferably of a size sufficient to hold two cube trays. whensuperimposed on each other and a supporting lid or plate 30 ispreferably placed on the lower trays which is inserted in this unit inorder to receive and support a second tray. The lower unit, shown inFig. 4, is intended to receive but a single tray.

In the construction shown in Figs. 8, 9 and 10, the main body of theunit comprises a one-pieced casting 35 having an integral partition 36.Pressure plates 37, all of identical configuration, are applied to thetop face of the bottom 38 to the top face of said partition 36 and tothe bottom face of the top 39 of said unit, such pressure plates beingtightly secured in position by means of cap screws 40 which are threadedinto tapped bosses 4| provided on said pressure plates and as shown, theposition on the top plate is reversed with respect to that of the twolower pressure plates. In this construction as illustrated, the coilsare not shown, it being understood the same are applied and arrangedsimilarly to that of the coil shown in Figs. 3 and 4, except that itwill of course be understood that channelled boss 42 will be providedwith apertures through the wall thereof, as indicated by the numeral 43to permit of the emergence of the two legs of the coil into the top ofthe boss from the space m, the entrance into and emergence of the coilfrom the spaces 11 and o and also the entrance of the coil into thebottom of the boss 44 and the emergence of the same from the topthereof, such apertures being generally illustrated in Fig. 9.

In the construction shown in Figs. 11, 12 and 13, wherein is illustrateda built-up or sectional unit in which there is provided at the topthereof an ultra-rapid freezing compartment, the reference numeral 50designates a cast section which is provided with a flat bottom (or topwhen the same is inverted), and having identical lateral marginalflanges 5| which are provided with bosses 52 and 53 and vanes generallysimilar to the vanes shown in Figs. 1 to 3, said section being providedwith vanes 54 and 55 that are generally similar to the vanes shown inFigs. 1 to 3. Said bosses 53 are provided with a U-shaped channel 56similar to the bosses shown in Fig. 5. The

bosses 52 are cored or drilled to receive threaded carriage bolts 5'!that serve to maintain the sections in their assembled position. Saidsections, as shown, are provided with marginal spacing flanges 58 whichare adapted when two sections are inverted and their fiat faces areopposed to each other to form, in co-operation with a pressure plate onthe adjacent face of another section upon which it is superimposed,spaces or chambers p for the reception of the cooling coil l5 which islooped at the top in a manner generally similar to that shown in Fig. 5and at intermediate points is looped in the manner shown in Fig. 14 andat the bottom is looped in the manner similar to that shown in Fig. '7.The channels 56 are cut away, as indicated at 59, to admit of theentrance or emergence, or both, of the cooling coil into such channels,all in the manner generally explained in the construction previouslydescribed in connection with the construction in Figs. 1 to '7inclusive. The top and bottom pressure plates 50 and El aresubstantially identical and are provided with marginal spacing flanges62 which correspond to the spacing flanges 58 of the top and bottomsections respectively, thereby admitting of the cooling coil beingpositioned immediately above the top compartment and again immediatelybelow the lower compartment, and the inner faces of these plates are insufficiently close proximity to the face of the adjacent section toinsure that the spacing will be of the exact width necessary to insuresuccessive metal-to-metal contact between the pressure plates theadjacent flattened coil and the face of the respective section adjacentsuch coil. In the assembly of these sections into a complete unit, shownin Fig. 11, as well as if desired in the assembly of the sections shownin Figs. 1 to 3, it is desirable that the carriage bolts employed bethreaded throughout their length as illustrated at 1 in-Fig. l5 and thatthe adjacent walls .9 of some of the cooling sections be recessed toconform to one-half of a nut 63 applied to such bolt and thereby as thesections are being assembled, the nuts can be turned down or screwedhome upon each section and then the next section is applied and thecorresponding nut above the same is also screwed home, thus serving toincrease the rigidity of the entire assembly in addition to that whichwould be effected by merely employing the terminal hex nuts 28 appliedto the upper end of the carriage bolts.

A special pressure plate 64 is interposed between the bottom section ofthe upper compartment shown in Fig. 11 and the top section of the largecompartment therein shown and this plate is provided with marginalflanges 58 along the edges of the top and bottom faces thereof, therebyco-operating with the bottom face of the lower section of the topcompartment and the top face of the upper section of the largecompartment to form spaces 15 for the reception of the cooling coil,which spaces are generally similar in dimensions to the spaces p and ofthe requisite width to insure metal-tometal contact between theflattened coil inserted therein and the adjacent face of the pressureplate and the section to which it is applied.

In Fig. 17 a still further modification is illustrated which might betermed a duplex cooling unit which is adapted to receive trayspositioned side by side. The body of the unit shown may either comprisean open ended casting 10 having a sheet metal cover or top plate H spunthereover, or the top may be cast integral therewith so as to form aone-piece casting. Preferably, as shown, the side walls 12 of the unitat the bottom thereof, a shoulder 13 and av downwardly projecting flangeM are provided in order that a pressure plate 15 may be applied directlyon said shoulder so that the end of the same will lie within the flangeM, thus preventing any likelihood of the entrance of condensed moistureinto the space it occupied by the coil. The intake and outlet fittingsare carried by the bottom pressure plate and in this construction, asillustrated, it will be understood that although but one fitting isshown, namely the intake fitting is, that the other fitting ispositioned directly behind the same and therefore does not appear inthis illustration. However, it will be understood that the coil islooped so that one end is connected to the intake fitting I6 and fromthis the coil travels in a circuitous path generally similar to thatshown in Fig. 12 and the outlet leg passes first in proximity to thethermostatic well iii and thence directly to the outlet fitting, notshown.

As is apparent from the foregoing construction wherein I employsectional walls between which I secure a coil in metal-to-metal contactwith the adjacent faces of such walls, it is possible to diecast thecooling unit proper and the cover plate, whereas were the coil embeddedin such walls in the manner previously proposed, during the castingoperation, the pressure usually required in such die-casting or pressurecasting operation would objectionably distort, if not rupture, theembedded coil and likewise were such structure, having 'a coil casttherein, enameled, the temperature at which the enamelling was performedwould deleteriously affect or even melt the embedded coil even were itpossible to cast such a coil in a ferrous metal wall or a wall of othermetal which was suitable for the reception of enamel.

It is particularly desirable to form a cooling unit in the manner hereindescribed wherein the body proper is formed separately from the falseside walls, as ready access is thereby afforded to the coils for repairpurposes and thereby a defective coil could be readily repaired orrenewed without discarding the entire unit as would otherwise be thecase were the coil embedded in the side walls in the manner heretoforeproposed, see in this connection Reissue Patent No. 18,371.

In lieu of flattening the coil IS in the manner previously described,the same may be previously flattened prior to being applied to the mainbody of the unit, either by means of a hydraulic press or otherwise, andthen the pressure plates are thereafter applied and the cap screws 28are screwed down so as to intimately engage the flattened coil l5. Thislatter procedure is particularly desirable in the event the tube is ofrelatively tough metal, such as copper, since unless the walls of acopper tube are quite thin, it would require considerable pressure todeform the same to the extent indicated in Figs. 3 and l, Whereas on theother hand, if a lead coil is employed, as is usually preferred, it is acomparatively simple matter to deform the same by simply turning down onthe cap screws.

My investigations have led to the discovery that where enamelling of theexposed surfaces of the cooling units of automatic refrigeratingmachines is resorted to, as has been customary in the art for severalyears past, the efficiency of such units insofar as the ability of thesame to refrigerate the food compartment of the refrigerating machine isconcerned, can be very substantially increased by employing black enamelor very dark colored enamel which has a high index of heat rayabsorption in lieu of white orgray or other merely tinted enamel, suchas heretofore employed, which has a much lower index of heat ray absorption owing to the high index of reflection of heat rays possessed bywhite or light colored enamel surfaces. Furthermore, where enamelledsurfaces are employed, I have found that both the inner surfaces of themetal pressure plates and the adjacent metal surfaces of the body properof the cooling unit which are in contact with the cooling coils shouldbe left bare or unenamelled and only the inner and outer surfaces of theunit which are exposed to the circulating current of air within therefrigerator are enamelled. Another advantage of the black enamelledunit as herein described, resides in the fact that it serves to delimitthe layer of frost that tends to collect upon the unit during the normaloperation of the automatic refrigerating machine within which it isinstalled. This can be accounted for by the fact that the temperature ofthe outer surface of the black enamel unit will, owing to its tendencyto absorb rather than reflect heat rays from the circulating air in therefrigerator, be at a substantially higher temperature than that of asimilar unit having a white enamel or light colored enamel surface andtherefore, since in order for frost to accumulate, the outer surface ofthe frost layer must always be in excess of about 32 F., it will beevident from the foregoing that by accomplishing a greater absorption ofheat into the enamelled surface its temperature will be raised andconsequently it cannot support as thick a layer of frost as a similarunit having a white enamelled surface especially where the setting ofthe thermostat control is such as to maintain the food compartment atabout 45 F. which is approximately the optimum temperature for suchcompartments in household refrigerating machines.

It will be understood that while in the various units illustrated in thedrawings herein, the entire outer surfaces thereof may be of bare metal,nevertheless, it is preferable that in each unit the entire inner andouter surfaces which are exposed to the air currents of the refrigeratorshall be coated with black vitreous enamel of the usual thickness, say1/200", such as commonly employed for enamelled kitchen ware and thelike. Accordingly it will be understood that the units shown in Figs. 1,8, 11 and 16 have all of the surfaces of the shell or body which areactually exposed to the air currents of the refrigerator in which thesame are mounted and also the outer surfaces of all pressure platesemployed therein coated with vitreous enamel and preferably blackvitreous enamel, but the inner faces of such pressure plates and theopposing faces of the body or shell to which the same are applied are ofbare metal and unenamelled.

While I have described the employment of either a dummy pressure plateor a press for the purpose of flattening the coil 15 after the same hasbeen looped in the desired manner, such as illustrated in Figs. 5, 6, 7,12 and 14, it is to be understood this flattening can also be effected,where lead coils are employed, by applying the enamelled pressure plateand then applying the cap screws 28 to the bolts upon which the sectionshave been assembled whereupon such screws are screwed home until theflanges on the inner faces of the pressure plate are forced into contactwith the corresponding flanges on the walls of the section to which theyare applied, thereby effecting the flattening of the coil to anelliptical configuration wherein the two opposing flat sides are inintimate engagement with the adjacent walls of the pressure plate andsection to which the coil is applied, and the total length of theportion of the perimeter of the coil which is in metal-to-metal contactwith such pressure plate and the adjacent wall of such a section canthus be increased to over one-half the total perimeter of such coil, allas explained in my copending application No. 409,219 filed Nov. 23,1929, of which this application is a continuation in part.

The term sharp" as employed in the claims, denotes a unit or chamberwhich is keenly cold or biting cold, in the sense that this term iscommonly used with reference to sharp frost or sharp weather.

In the construction shown in Figs. 8, 9 and 10, wherein the pressureplates 31 are applied to the top of the bottom of the unit, to the topof the middle partition and to the bottom face of the top of the unit,there is an increased chilling effect imparted to cube trays positionedon these two lower pressure plates as contrasted with the cooling effecttransmitted to cube trays inserted in the compartments shown in Figs. 3and 4 or in the three lower compartments shown in Fig. 1.1, for thereason that in the construction shown in the latter three figures, theslab or plate on which the cube trays rest, is integral with the sidewalls or at least with one-half of the side walls of the cooling sectionor compartment in which the trays are positioned and consequently thereis a more substantial interchange of heat between the side walls andtheir integral fins with said integral slab, than is the case where, asshown in Figs. 8 and 10, the pressure plates are a separate entity fromthe Walls of the section or unit. As a result, the extremely rapidfreezing of ice cubes in cube trays positioned on the plates 31 can beaccomplished without the temperature of the food compartment, which ismore directly responsive to the actual temperature of the side walls andthe integral fins, as well as the top and bottom walls of a unit orsection, dropping to as low a temperature as would be the case were theconstruction shown in Figs. 3, 4 and 11 employed.

In Fig. 1'7, I have illustrated a cooling unit which, as illustrated, isnot enamelled, but the same is formed entirely of metal and the traysupporting surface, as well as the surfaces in contact with the coilsand all the external surfaces and fins of the unit are of bare metal,although, if desired, the surfaces of this unit, other than those incontact with the coil, may be coated with a vitreous or so-calledporcelain enamel. Likewise, it will, of course, be understood that anyof the other units may be formed with bare metal surfaces throughout, inlieu of having the exposed surfaces enamelled, as is usually preferred,or if desired, merely the top surface of the transverw tray supportingslabs and the inner surfaces of the chambers containing the coils, maybe formed of bare metal and the balance of the surfaces of such unit maybe coated with enamel.

While the tubing, when originally bent to form the loops of the desiredconfiguration is preferably circular in cross-section, it may, ofcourse, be flattened to any desired extent before forming the tubinginto coils.

A particular advantage of my improved construction is the fact that byvirtue of its sectional construction, I have been able to interposerefrigerant coils beneath the tray supporting slabs with which the sameis in intimate metal-to-metal contact and at the same time, the sidewalls of the unit, which are relatively remote from such coils, will becooled only through the indirect conduction of the heat from such sidewalls and the vanes carried thereby to the coils, as there is noextended contact between such side walls and the vanes thereon with thecoils as such, in fact, in the construction shown, there is no directcontact at all therebetween. As a result, it is possible to obtainremarkably quick freezing of ice cubes or other liquids placed on thetray supporting slabs while at the same time through suitablyproportioning the superficial area of the vanes carried thereby to thesize of the refrigerator to be cooled, it is possible to maintain thefood chamber at the optimum temperature of about 45 F., even though therate of freezing ice cubes of standard size can be maintained at a highrate not exceeding substantially 14 hours, whereas ordinarily with otherunits commonly employed, such rapid freezing of ice cubes can only beaccomplished by the employment of a cold control device for acceleratingthe cooling of the unit, with the consequence, that unless such coldcontrol is turned off when the cubes are frozen, the entire ice-boxtemperature Will be reduced to a deleterious temperature and result inthe freezing or excessive chilling of many sensitive substances storedin the food chamber.

When employing a press for flattening the coils in situ, the latter areapplied to the desired surfaces of the unit and the pressure plates ofthe unit may be positioned on top of such coils and then the platen ofthe press caused to bear thereon until the coils are flattened to thedesired extent and then while the pressure is still being applied, thepressure plates and unit sections can be screwed together by screwingdown the cap screws on the top of the retaining bolt members, afterwhich the pressure is released and the unit with the parts completelyassembled removed from the unit.

The cooling unit illustrated herein lends itself to be made of aluminum,iron or other suitable metal and the separate sections thereof maycomprise metal stampings or may be cast in sand molds or produced by apressure die-casting operation.

By the term intimate contact, as used in the claims, I contemplatemetal-to-metal contact as distinguished from the contact whichwould-result were a layer of enamel to be interposed between the coiland the adjacent surface to which it was applied. Furthermore, by theterm line contact, as used in the claims, I contemplate contact in aplane corresponding to a cross-section through the coil and the surfacesof the adjacent walls of the pressure plate or section, as distinguishedfrom the substantial point contact in the same plane of a tube ofcircular cross-section when a flat surface is brought into intimatecontact therewith.

Various modifications within the scope of the appended claims may bemade without departing from the spirit of my invention.

Having thus described my invention, what I claim is:

1. An expansion cooling unit for automatic refrigerating machines,comprising a main body having the side, top and bottom thereof integral,a cooling chamber therein, hollow means for maintaining a refrigerantfluid in intimate heatexchange with at least one of the walls of saidsharp cooling chamber, vertically extending grooved bosses, integrallyformed on said body, positioned at the rear thereof and into which aportion of the aforesaid hollow means extends and, a pressure plateapplied to one of the walls of such body and in intimate heat-exchangerelation with such hollow means.

2. An expansion cooling unit for refrigerating machines, comprising amain body having a plurality of adjacent sharp cooling chambers therein,such main body being formed of a plurality of substantially similarsections associated together with certain of the adjacent sections beinginverted with respect to each other and serving to form a sharp coolingchamber and a plurality of looped metal coils interconnected with eachother for refrigerant fluid disposed in two diiferent substantiallyparallel transverse planes in close proximity to each other andintermediate two adjacent sharp cooling chambers of such unit and aportion of one coil being in direct metal-to-metal contact with theouter wall of one cooling chamber and a portion of the other coil beingin direct metal-to-metal contact with the outer wall of an adjacentcooling chamber and said unit having a pressure plate which isinterposed between said coils and is in intimate metalto-metal contacttherewith.

3. A sectional expansion cooling unit for refrigerating machines,comprising a plurality of superimposed sections of generally similarconfiguration, the adjacent sections being inverted with respect to eachother, certain of the Walls of said sections having vertical aperturesadapted to register with each other when such sections are superimposedwith respect to each other, bolts in said apertures and certain of saidapertures being enlarged at the ends thereof to form a nut-receivingrecess and nuts threaded on such bolts and positioned intermediate theends thereof when such unit is assembled, said nuts lying within theterminal recesses aforesaid and terminal nuts on said bolts forco-operating with such intermediate nuts for holding the assembledsections in their assembled relation.

4. A sectional cooling unit for automatic refrigerating apparatus,having a sharp cooling chamber therein, the bottom of said coolingchamber being formed hollow and in sections, a refrigerant coilinterposed between opposing sections of said bottom and having extendeddirect physical contact with the opposing sections thereof and saidsharp cooling chamber having its vertical side walls out of extendeddirect contact with said refrigerant coils, but being indirectlymetallically connected therewith, whereby intense rapid cooling of cubetrays positioned in said sharp cooling chamber can be effected withoutcausing the mean temperature of the air in the compartment of arefrigerator in which the unit is mounted to fall below the optimumoperating temperature desired therein.

ALEXANDER S. LIIVLPERT.

